ASTM D91-02(2012)
(Test Method)Standard Test Method for Precipitation Number of Lubricating Oils
Standard Test Method for Precipitation Number of Lubricating Oils
SIGNIFICANCE AND USE
4.1 Fully refined petroleum oils normally contain no naphtha insoluble material. Semirefined or black oils frequently contain some naphtha insoluble material (sometimes referred to as asphaltenes ). This test measures the amount of naphtha insoluble material in the oil. This quantity is reported as the precipitation number.
SCOPE
1.1 This test method covers the determination of the precipitation number of steam cylinder stocks and black oils, and can be used for other lubricating oils.
1.2 The values stated in acceptable SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D91 − 02(Reapproved 2012)
Standard Test Method for
1,2
Precipitation Number of Lubricating Oils
This standard is issued under the fixed designation D91; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope to as asphaltenes ). This test measures the amount of naphtha
insoluble material in the oil. This quantity is reported as the
1.1 This test method covers the determination of the pre-
precipitation number.
cipitation number of steam cylinder stocks and black oils, and
can be used for other lubricating oils.
5. Apparatus
1.2 The values stated in acceptable SI units are to be
5.1 Centrifuge Tube, cone-shaped, conforming to the di-
regarded as the standard.
mensions given in Fig. 1, and made of thoroughly annealed
1.3 This standard does not purport to address all of the
glass. The graduations, numbered as shown in Fig. 1, shall be
safety concerns, if any, associated with its use. It is the
clearanddistinct,andthemouthshallbeconstructedinashape
responsibility of the user of this standard to establish appro-
suitable for closure with a cork. Scale-error tolerances and
priate safety and health practices and determine the applica-
smallest graduations between various calibration marks are
bility of regulatory limitations prior to use.
given in Table 1 and apply to calibrations made with air-free
water at 20°C.
2. Referenced Documents
5.2 Centrifuge, meeting all the safety requirements for
2.1 ASTM Standards:
normal use and capable of whirling two or more filled
D4057 Practice for Manual Sampling of Petroleum and
centrifuge tubes at a speed which can be controlled to give a
Petroleum Products
relative centrifugal force (rcf) between 600 and 700 at the tip
D4177 Practice for Automatic Sampling of Petroleum and
of the tubes. The revolving head, trunnion rings, and trunnion
Petroleum Products
cups, including the rubber cushion, shall be soundly con-
structed to withstand the maximum centrifugal force capable of
3. Terminology
being delivered by the power source. The trunnion cups and
3.1 Definitions of Terms Specific to This Standard:
cushions shall firmly support the tubes when the centrifuge is
3.1.1 ASTM precipitation number, of lubricating oils, n—the in motion.The centrifuge shall be enclosed by a metal shield or
number of millilitres of precipitate formed when 10 mL of
case strong enough to eliminate danger if any breakage occurs.
lubricating oil are mixed with 90 mL of ASTM precipitation Calculate the speed of the rotating head by means of the
naphtha, and centrifuged under the conditions of the test.
following equation:
rpm 5 1337 =rcf/d (1)
4. Significance and Use
where:
4.1 Fully refined petroleum oils normally contain no naph-
tha insoluble material. Semirefined or black oils frequently
rcf = relative centrifugal force, and
contain some naphtha insoluble material (sometimes referred d = diameter of swing, in mm, measured between tips of
opposite tubes when in rotating position.
Table 2 shows the relationship between diameter swing, rcf,
This test method is under the jurisdiction of ASTM Committee D02 on
and revolutions per minute.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.06 on Analysis of Lubricants.
6. Reagent
Current edition approved Nov. 1, 2012. Published November 2012. Originally
approved in 1921. Last previous edition approved in 2007 as D91 – 02 (2007). DOI:
6.1 Hexanes, Reagent Grade. (Warning—Extremely
10.1520/D0091-02R12.
flammable, harmful if inhaled.)
This test method has been adopted for use by government agencies to replace
Method 3101 of Federal Test Method Standard No. 791b.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 7. Sampling
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
7.1 For sampling techniques, see Practices D4057 or Prac-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tice D4177.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D91 − 02 (2012)
at 32 to 35°C for 5 6 1 min. Momentarily remove the corks to
relieve any pressure, and invert each tube again at least 20
times exactly as before. The success of this method depends to
a large degree upon having a
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